Process of treating oils



Patented Nov. 13, W23.

FREDERICK w. na'zann, or cmis'rnn, rnnnsrnvamn,

DE nnmouas a comranr, or WILMINGTON,

DELAWARE.

ASSIGNOR TO E. I. DU FONT DELAWARE, A CORPORATION OF PRooE'ss or TREATING 0113s.

No Drawing.

. The object of my invention is to provide a process by means of which hydrocarbons, such for example as benzol, toluol andsolvent naphtha, may be washed to free the same from heavy materials without any great loss of said hydrocarbons. Previously in the treatment of hydrocarbons of this character it has been customar after obtaining said oils by distilling t e tars and mineral oils containing the same so as to separate the latter from the high boiling constituents, to wash the low'boiling distillate'a' number of times with concentrated sulfuric acid, that is to say of approximately 66 B. specific gravity, in order to remove the olefines and other unsaturated compounds. The oil, after having been purified in this manner, was washed with water and .with a dilute solution of an alkali, inorder to remove the excess acid, and thereafterthe resulting oils were rectified for the production of pure benzol, toluol and solvent naphtha, the latter being principally comprised of xylol.

When the washing is carried out in this -way, the first washlng with sulfuric acid results in the production of a heavy viscous tar, which I have discovered carries with it a quantity of entrained hydrocarbons, that is to say, benzol, toluol and solvent naphtha, which can neither be removed by allowing the sludge acid to settle nor by drowning in water.

The object of my invention is to carry out the washing process so as to remove the olefines and other unsaturated compounds without a great loss of the hydro-- Application filed ning'ust 17, 1918. Serial No. 250,310.

carbons, that is to say, benzol, toluol and solvent naphtha.

I have discovered that, if the first washing is carried out by the use of dilute sulfuric acid, a sludge acid is formed which can be drawn off in a very fluid state, carrying the tars in solution and entraining only a very small quantity of the hydrocarbon oils, and, furthermore, that when thereafter the washing is carried out with concentrated surfuric acid, 66 B., the strong acid Washes do not contain tar nor any entrained oils.

While my invention is capable of'being carried out in many difi'erent ways, for the purpose of illustration I shall describe herein only one way of carrying out the same.

For example, I ma proceed as follows: A quantity of the 0115 containing benzol, toluol and solvent naphtha (that is to say, xylol), and which have been obtained by distillation of tars or mineral oils bearin these constituents, is thoroughly agitated with a quantity of dilute sulfuric acid, which may have a strength of 75%, and equal in weight to 1.5% of the oil being treated, and whilethe temperature is from 25 to 40 C. The liquids are allowed to settle and the sludge acid is withdrawn. Thereafter the hydrocarbon oils are subjected to two additional washings, in each of which sulfuric acid of the same strength is used but equal to 3% by weight of the hydrocarbon oils. After each such additional washing, the washing acid is removed preparatory to submitting the hydrocarbon oils to the succeeding washing step. After the third washing above referred to has been given, the hydrocarbon oils are subjected to a fourth washing with 10% strength sulfuric acid, equal in weight to 4% of the-hydrocarbon oils, this washing being for the purpose of removing from the sides of the container any small amount of tar which may have been formed and e which has remained therein.

The hydrocarbon oils are then subjected to a number of additional washings in a similar manner with 90% strength sulfuric acid, each of said washings being conducted with a quantity of said sulfuric acid e ual in weight to 2.5% of the hydrocarbon oi s, such washings being applied until the hydrocarbon oil has been properly purified. T hereupon the said oils are washed a sufiicientnumber of times with water and a dilute alkali, that is to say an aqueous solution of sodium hydrate having a strength of 20 B. to neutralize the excess acid.

The resultant washed oils are now ready for rectification, and they are, therefore,

now distilled to produce pure benzol, toluol and solvent naphtha.

In the first washing with dilute sulfuric acid, sulfuric acid of any strength may be used up to sulfuric acid having a strength of 80%. It is desirable, however, not to have the sulfuric acid that is used for this purpose too dilute, as, if very dilute sulfuric acid is used, many washings will be required. The best results are obtained by the use of sulfuric acid having a strength of 70% to 75%.

While I have described my invention above in detail, I wish it to be understood that, many changes may be made therein without departing from the spirit of the invention.

I claim:

1. The process of removing olefines and other unsaturated compounds from a coal tar distillate composed chiefly of the arcmatic hydrocarbons benzol, toluol and solvent naphtha, while avoiding great loss of aromatic hydrocarbons, which comprises washing said distillate with dilute sulfuric acid of from about to strength to form a sludge acid containing tar, allowing the mixture to settle, and separating the sludge acid from the mixture of aromatic hydrocarbons.

2. The process of removing olefines and other unsaturated compounds from a coal tar distillate composed chiefly of the aromatic hydrocarbons benzol, toluol and solvent naphtha, while avoiding great loss of aromatic hydrocarbons, which comprises washing said distillate with a dilute sulfuric acid of from about 70 to- 75% strength to form a sludge acid containing tar, allowing the mixture to settle, separating the sludge acid from the mixture of aromatic. hydrocarbons, and subsequently washing the arcmatic hydrocarbon mixture with concentrated sulfuric acid.

3. The process of removing olefines and other unsaturated compounds from a coal tar distillate composed chiefly of the aromatic hydrocarbons benzol, toluol and solvent naphtha, while avoiding gleat loss of aromatic hydrocarbons, which comprises washing said distillate with dilute sulfuric acid of from about 70 to 75% strength to form a sludge acid containing tar. allowing the mixture to settle, separating the sludge acid from the mixture of aromatic hydrocarbons, and subsequently washing the aromatic hydrocarbon mixture with sulfuric acid of about 90% strength.

4. The process of removing olefines other unsaturated compounds from a coal tar distillate composed chiefly of the aromatic hydrocarbons benzol, toluol and solvent naphtha, while avoiding great loss of aromatic hydrocarbons. which comprises washing said distillate with dilute sulfuric acid of from about 70 to 75% strength, the amount used being equal to about 1.5% by weight of the distillate, and repeating the washingone or more times with the same strength acid but with an amount of acid for each washing equal to about 3% by weight of the oil being treated, the sludge acid being withdrawn after each washing operation.

5. The process of removing olefines and other unsaturated compounds from a coal tar distillate composed chiefly of the arematic hydrocarbons benzol, toluol and solvent naphtha, while avoiding great loss of aromatic. hydrocarbons, which comprises washing said distillate with dilute sulfuric acid of from about 70 to 75% strength, the amount used being e ual to about 1.5% by weight of the dist1llate, repeating the washing one or more times with the same strength acid but with an amount of acid for each washing equal to about 3% by weight of the oil being treated. the sludge acid being withdrawn after each washing operation, and subsequently subjecting the aromatic hydrocarbon mixture to one or more washings with sulfuric acid of about 90% strength, the amount of acid used for each such washing being equal to about 2.5% of the weight of the oil being treated.

6. The process of removing olefines and other unsaturated compounds from a coal tar distillate composed chiefly of the aromatic hydrocarbons benzol, toluol and solvent naphtha, while avoiding great loss of aromatic hydrocarbons, which comprises washing said distillate with dilute sulfuric acid of from about 70 to 75% strength to form a sludge acid containing tar, allowing the mixture to settle, separating the sludge acid from the mixture of aromatic hydrocarbons, and subsequently subjecting the aromatic hydrocarbon mixture to one or more washin s with sulfuric acid of about 90% strength, the amount of acid used for each such washing bein equal to about 2.5% of the weight of the Oll being treated.

7. The process of removing olefines and other unsaturated compounds from a coal tar distillate composed chiefly of the aromatic hydrocarbons benzol, toluol and solvent naphtha, while avoiding great loss of aromatic. hydrocarbons, which comprises subjecting said distillate to two or more and washings with dilute sulfuric acidto remove In testimony that I claim the foregoing tarry matter without entrainment of a sub- I have hereunto set my hand. stantial amount of benzol, toluol or solvent naphtha, and then to a number of washings FREDERICK BAYARD' 6 with concentrated sulfuric acid until the Witnesses:

aromatic hydrocarbons have been purified J. M. CoWoILL,

to the desired degree. J. A. MONKMAN. 

